lkml.org 
[lkml]   [2017]   [Jul]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH -tip v5 2/2] [BUGFIX] kprobes/x86: Do not jump-optimize kprobes on irq entry code
Date
Since the kernel segment registers are not prepared at the
entry of irq-entry code, if a kprobe on such code is
jump-optimized, accessing per-cpu variables may cause
kernel panic.
However, if the kprobe is not optimized, it kicks int3
exception and set segment registers correctly.

This checks probe-address and if it is in irq-entry code,
it prohibits optimizing such kprobes. This means we can
continuously probing such interrupt handlers by kprobes
but it is not optimized anymore.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reported-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Tested-by: Francis Deslauriers <francis.deslauriers@efficios.com>
---
Changes in v5:
- Use CONFIG_IRQENTRY.
---
arch/Kconfig | 1 +
arch/x86/kernel/kprobes/opt.c | 9 ++++++---
2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 21d0089117fe..f006af0d8c9e 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -91,6 +91,7 @@ config OPTPROBES
def_bool y
depends on KPROBES && HAVE_OPTPROBES
depends on !PREEMPT
+ select IRQENTRY

config KPROBES_ON_FTRACE
def_bool y
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 69ea0bc1cfa3..c26e7f989c7d 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -29,6 +29,7 @@
#include <linux/kallsyms.h>
#include <linux/ftrace.h>
#include <linux/frame.h>
+#include <linux/interrupt.h>

#include <asm/text-patching.h>
#include <asm/cacheflush.h>
@@ -251,10 +252,12 @@ static int can_optimize(unsigned long paddr)

/*
* Do not optimize in the entry code due to the unstable
- * stack handling.
+ * stack handling and registers setup.
*/
- if ((paddr >= (unsigned long)__entry_text_start) &&
- (paddr < (unsigned long)__entry_text_end))
+ if (((paddr >= (unsigned long)__entry_text_start) &&
+ (paddr < (unsigned long)__entry_text_end)) ||
+ ((paddr >= (unsigned long)__irqentry_text_start) &&
+ (paddr < (unsigned long)__irqentry_text_end)))
return 0;

/* Check there is enough space for a relative jump. */
\
 
 \ /
  Last update: 2017-07-27 18:21    [W:0.058 / U:46.024 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site